I went along the following line of thought. I put access to Internet as one of the major requirements at pointReturn - for me, and visitors and residents to come. Electric lighting too is a requirement, economised by use of CFLs and LEDs. I considered power tools - a drill, a saw etc- as essential too. I could use rechargeable tools but some would need to be plugged in. I can foresee buying an electric two wheeler for local runs; this too would need premium grade electricity to charge. Thus far, a windmill has been pumping water but a standby electric pump would be useful.

Turning to pattern of use, currently pointReturn has no full time resident. They will come and the need would grow. Right now, lighting, charging phones and a lap-top and running a drill are the weekly needs. So I picked on a power plant size that is not so skimpy that it would be insufficient in the near term nor so large that it would not be useful till many years later.

Without further ado let me list the parts of the installed plant before I make some further comments. Names mentioned are brands

1. Solar panel - 90 watts - Tata-BP Solar
   This is mounted on the roof of the strong room, inclined 15deg facing south. A cable leads down to the interior of the strong room. 10 year warranty.Link
2. Charge controller - 10amps - Phocos
   This device senses the level of charge in the batteries and prevents over charging. The system required only a 5 amps charger; buying a very nominally higher priced controller will enable me to add another 90w solar panel later. 1 year warranty
3. Batteries - 12v 200 ampere hours [AH] each - 2 numbers - Exide
   This is an ample size to ride out up to a week of cloudy days. These are specially suited for solar/standby power use and are often referred to as deep cycle batteries. 3 year warranty.Link
4. Pure sine-wave inverter - 700 watts - Conergy:
   This is a premium product that cost almost thrice the popular brands. It converts 12v DC into premium 220v-50Hz pure sine wave electricity. This is a solid state model, solar energy system specific and reputedly popular worldwide.Link
5. System integrator: Aurore
   This company located in Auroville, near Pondicherry has a good record of service in and around Chennai. Link

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